1. Field of the Invention
The present invention relates to electrical connectors for flat cables, and more particularly relates to a low insertion force (LIF) connector for providing an external electrical interface for an internal flat cable of an electrical device.
2. Description of Prior Art
Use of low insertion force (LIF) and zero insertion force (ZIF) connectors on printed circuit boards for receiving a flexible printed circuit (FPC) or a flexible flat cable (FFC) is well known in the field. LIF and ZIF relate to the technology of providing an electrical connector with the means in which conductors are inserted into the connector under relatively friction free and damage free conditions. Such connectors are typically soldered or otherwise affixed to an internal circuit board of an electrical device. An FPC or FFC is inserted into the connector and held in place to ensure positive electrical contact between the conductors of the FPC or FFC and the terminals of the connector. Various means of inserting and holding the FPC or FFC using low or zero insertion force are used to prevent damage to the FPC or FFC or damage to the components of the connector.
For example, U.S. Pat. No. 5,562,487 to Ii et al. discloses an electrical connector having an actuator which is slidably inserted in the connector housing. The actuator has a flat surface portion upon which a flat flexible cable may lie during friction free insertion of the actuator and cable into the housing. Thus inserted, the flexible flat cable makes electrical contact with the terminals of the connector. The terminals include solder tails which extend out of the connector housing which are soldered to a printed circuit board.
Similarly, U.S. Pat. No. 4,640,562 to Shoemaker discloses a surface mounting means for an electrical connector to a printed circuit board which includes a wedge plate for forcing contact of the flexible cable to the terminals of the connector. The connector is releasably mounted to the surface of the circuit board making electrical contact between the terminals and the conductors of the circuit board. These and other LIF and ZIF connectors provide efficient, damage free electrical connection between flexible flat cables or flexible printed circuits and internal circuit boards.
Each of the above described connectors are designed to establish LIF or ZIF interconnection to internal components of an electrical device. However, the use of LIF or ZIF termination technology has not been shown in an external environment. Certain electrical devices, such as personal computers and disk drives, require an external interface for an internal component. A multi-pin connector is typically provided on such devices to connect a flexible flat cable to an external port of the device. FIG. 1 shows a conventional external multi-pin connector 100 for a flat flexible cable 101. The conventional connector 100 is provided with box-pin terminals 102 having solder tails 103 which engage through holes of the flat flexible cable. A strain relief bar 104 is also provided on the connector to hold the cable in place. Once the flat flexible cable 101 is linked to an internal component of the device, such as a printed circuit board or a hard disk actuating arm, the other end of the cable is connected to the external connector by through hole tin-lead soldering. This process tends to be costly and intricate as the soldering operation involves targeting the through holes of the flex cable to the solder tails after passing the cable through the connector's strain relief bar.
Accordingly, it is desirable to provide ZIF or LIF technology to an external connector for a flat flexible cable extending from an internal component which in turn would provide quick and easy connection and disconnection between the flat flexible cable and the external connector.